Weekly Warfarin Self-Testing Improved INR Control

Individuals taking warfarin who engaged in weekly patient self-testing (PST) had significant improvement in control of warfarin compared to patients who had variable (1–4 tests per month) self-testing. These findings, which were from the largest study of warfarin patient self-testing to date, were published in the American Journal of Managed Care.

Grace DeSantis, PhD, and colleagues conducted a retrospective analysis using data from the Self-Testing Analysis Based on Long-Term Evaluation (STABLE) study of patients on warfarin from January 2008–June 30, 2011 for control of warfarin as measured by time in therapeutic range (TTR). A total of 29,457 patients ranging in age from 18–105 years at the start of PST were evaluated, with 80% being ≥65 years of age, 56% male, and atrial fibrillation (AF) as the primary diagnosis for anticoagulation therapy with warfarin.

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Patients 65–74, 75–79, and 80–84 years of age all had higher TTR rates (71.5%, 70.8%, 68.9% respectively) compared to patients 46–64 years of age (67.0%). Variable/non-weekly testers were more likely to fall in the low TTR group, compared with the weekly PST group (29.8% vs. 17.1%, 95% CI 1.89–2.22). Also, weekly testers experienced significantly fewer critical international normalized ratio (INR) values <1.5 or >5.0 as compared to the variable testers.

Unlike previous studies, this is the largest analysis to date of warfarin patient dosage management through a home PST scenario in a real-world setting. The authors conclude that weekly testing is the best means of minimizing critical value risk due to the low incidence in patients with high TTR.

For more information visit the American Journal of Managed Care website.

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